Heat exchanger and water heating device including same

ABSTRACT

Provided is a heat exchanger which includes a plurality of meandering heat transfer pipes that includes first and second heat transfer pipes, as the plurality of heat transfer pipes, which are adjacent to each other in a predetermined y direction and are misaligned with each other in a z direction such that a plurality of straight pipe parts are in a non-overlapping state in the y direction, in which a first recessed part recessed in the y direction is provided in each curved pipe part of the first heat transfer pipe, and a part of each curved pipe part of the second heat transfer pipe is fitted into the first recessed part.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Japan application serial no. 2020-068371, filed on Apr. 6, 2020. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND Technical Field

The disclosure relates to a type of heat exchanger that is used as a component of a water heating device such as a hot water supply device and recovers heat from a heating medium such as combustion gas by using a heat transfer pipe, and a water heating device including the same.

Description of Related Art

As an example of a heat exchanger, there is one described in Patent Document 1.

In the heat exchanger described in the same document, a meandering heat transfer pipe is used for a heat transfer pipe for recovering heat from combustion gas. The meandering heat transfer pipe has a configuration in which a plurality of straight pipe parts are connected to each other via a plurality of curved pipe parts. In the above document, a plurality of heat transfer pipes are used for such a meandering heat transfer pipe, and these are stacked in a vertical height direction, for example. Further, it is conceivable that heat transfer pipes adjacent to each other be set, for example, in an array in which they are displaced from each other in a horizontal direction so that combustion gas can easily act on each heat transfer pipe.

On the other hand, in the heat transfer pipes, the curved pipe parts are processed into flat shapes and have thicknesses smaller than those of the straight pipe parts. This makes it possible to bring heat transfer pipes adjacent to each other close to each other. As a result, it is possible to reduce a width of the entire plurality of heat transfer pipes in the stacking direction and to reduce a size of the entire heat exchanger.

However, according to the above-mentioned conventional technique, there is still room for improvement as described below.

First, since the entire curved pipe parts of the meandering heat transfer pipes are formed in flat shapes, there is a disadvantage that the resistance (flow path resistance) when a fluid to be heated flows through the inside of the heat transfer pipe increases.

Secondly, since an amount of processing for forming the entirety of each curved pipe part into a flat shape is large, a residual stress increases. This causes stress cracking in the heat transfer pipe, which is not preferable. When the heat exchanger is used, a large pressure may act on the heat transfer pipe due to, for example, a water hammer phenomenon, and thus it is desirable to reduce the above-mentioned residual stress as much as possible.

Thirdly, as a means for forming each curved pipe part of the meandering heat transfer pipe in a flat shape, for example, as shown in FIG. 13, a means for pressing a curved pipe part 21 of a heat transfer pipe 2 e in a direction intersecting a bending direction of the curved pipe part 21 is conceivable. However, when such pressing is performed, as shown by arrows Na, a force that tends to deform both ends of the curved pipe part 21 in a direction in which they are widened is generated. In Patent Document 1, since the amount of pressing is large, the above-mentioned deformation is likely to occur, and there is concern that the heat transfer pipe 2 e may differ from original specifications.

Patent Documents

[Patent Document 1] Japanese Patent No. 4143431

SUMMARY

A heat exchanger provided according to an embodiment of the disclosure includes a plurality of heat transfer pipes that have a meandering shape, in which a plurality of straight pipe parts that extend in an x direction among x, y, and z directions intersecting with each other and are arranged at intervals in the z direction are connected in a series via a plurality of curved pipe parts, and are located in a region through which a heating medium flows and stacked in the y direction. The plurality of heat transfer pipes comprises a first heat transfer pipe and a second heat transfer pipe, which are adjacent to each other in the y direction and misaligned with respect to each other in the z direction such that, in a view in the y direction, the plurality of straight pipe parts are in a non-overlapping state and parts of the plurality of curved pipe parts are in an overlapping state. A first recessed part recessed in the y direction is provided in a part of each curved pipe part of the first heat transfer pipe, and a part of each curved pipe part of the second heat transfer pipe is fitted into the first recessed part.

A water heating device provided according to an embodiment of the disclosure includes the heat exchanger mentioned above.

Other features and advantages of the disclosure will become apparent from the following description of embodiments of the invention with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view showing an example of a heat exchanger according to the disclosure.

FIG. 2 shows a schematic configuration of a water heating device using the heat exchanger of FIG. 1, and the heat exchanger shown by the solid line in the figure corresponds to a cross-sectional view along line II-II in FIG. 1.

FIG. 3 is a cross-sectional view along line III-III in FIG. 1.

FIG. 4 is a perspective view showing heat transfer pipes (first and second heat transfer pipes) used in the heat exchanger shown in FIGS. 1 to 3.

FIG. 5A is a front view of a main part of the heat transfer pipes shown in FIG. 4, FIG. 5B is a cross-sectional view along line VB-VB in FIG. 5A, FIG. 5C is a side view along arrow VC in FIG. 5A, FIG. 5D is a cross-sectional view along line VD-VD in FIG. 5A, and FIG. 5E is a cross-sectional view along line VE-VE in FIG. 5A.

FIG. 6A is a front view of a main part in a state in which the heat transfer pipes shown in FIG. 5A are stacked, FIG. 6B is a cross-sectional view along line VIB-VIB in FIG. 6A, and FIG. 6C is a cross-sectional view along line VIC-VIC in FIG. 6A.

FIG. 7 is a perspective view showing another example of the disclosure.

FIG. 8A is a front view of a main part of the heat transfer pipes shown in FIG. 7, FIG. 8B is a cross-sectional view along line VIIIB-VIIIB in FIG. 8A, and FIG. 8C is a cross-sectional view along line VIIIC-VIIIC in FIG. 8A.

FIG. 9 is a perspective view showing another example of the disclosure.

FIG. 10A is a front view of a main part of the heat transfer pipes shown in FIG. 9,

FIG. 10B is a cross-sectional view along line XB-XB in FIG. 10A, and FIG. 10C is a cross-sectional view along line XC-XC in FIG. 10A.

FIG. 11 is a perspective view showing another example of the disclosure.

FIG. 12A is a front view of a main part of the heat transfer pipes shown in FIG. 11,

FIG. 12B is a cross-sectional view along line XIIB-XIIB in FIG. 12A, and FIG. 12C is a cross-sectional view along line XIIC-XIIC in FIG. 12A.

FIG. 13 is an explanatory diagram showing an operation in a conventional technique.

DESCRIPTION OF THE EMBODIMENTS

According to an embodiment of the disclosure, the disclosure provides a heat exchanger that can solve problems such as an increase in flow path resistance of a meandering heat transfer pipe and a large amount of residual stress generated in the heat transfer pipe and can appropriately achieve overall reduction in size, and a water heating device including the heat exchanger.

According to an embodiment of the disclosure, each curved pipe part of the first heat transfer pipe comprises a pair of side surface parts facing in the y direction, and the first recessed part is provided in each of the pair of side surface parts.

According to an embodiment of the disclosure, each curved pipe part of the first heat transfer pipe comprises a pair of side surface parts facing in the y direction, and the first recessed part is provided only on one of the pair of side surface parts.

According to an embodiment of the disclosure, a second recessed part recessed in the y direction is provided in a part of each curved pipe part of the second heat transfer pipe, and respective formation places of the first and second recessed parts are fitted to each other.

According to an embodiment of the disclosure, the second heat transfer pipe has a configuration coincides with a configuration of a heat transfer pipe having a same shape and size with the first heat transfer pipe and has been turned upside down.

According to an embodiment of the disclosure, the first and second heat transfer pipes are configured by using metal round pipes.

According to an embodiment of the disclosure, the heat exchanger according to the disclosure further comprises a case which houses the first and second heat transfer pipes therein and the heating medium is supplied to an inside of the case, and a pair of header parts for inflow of water and outflow of hot water for each of the first and second heat transfer pipes.

According to an embodiment of the disclosure, the x and y directions are both horizontal directions, and the z direction is a vertical height direction.

Hereinafter, preferred embodiments of the disclosure will be specifically described with reference to the drawings.

A heat exchanger HE shown in FIGS. 1 to 3 includes a case 1, a plurality of heat transfer pipes 2 having a meandering shape, and a pair of header parts 7 a and 7 b for inflow of water and outflow of hot water.

The case 1 has a substantially rectangular tubular shape or a frame shape with an upper surface part and a lower surface part being open, and a heating medium is supplied to the inside of the case 1.

FIG. 2 shows a water heating device WH using the heat exchanger HE. In this water heating device WH, a burner 80 and another heat exchanger 81 are provided on an upper side of the case 1. Another heat exchanger 81 is a primary heat exchanger for sensible heat recovery, and the heat exchanger HE of the present embodiment is a secondary heat exchanger for latent heat recovery. In the water heating device WH, combustion gas (heating medium) generated by the burner 80 travels downward and sequentially passes through the heat exchanger 81 and HE, whereby sensible heat and latent heat are sequentially recovered from combustion gas, and hot water heating is performed using the recovered heat. This hot water is supplied to, for example, a hot water tap in a kitchen, a hot water tap in a bathroom, or a bathtub.

The plurality of heat transfer pipes 2 are meandering heat transfer pipes formed by using round pipes made of a metal such as stainless steel and are housed in the case 1. More specifically, as clearly shown in FIG. 3, each heat transfer pipe 2 has a meandering shape in which a plurality of straight pipe parts 20 that extend in a front to rear direction (an example of the x direction in the disclosure) of the case 1 and are arranged at intervals in a vertical height direction (an example of the z direction in the disclosure) are connected in a series via a plurality of curved pipe parts 21 having semicircular arc shapes in a side view.

Both end parts of each heat transfer pipe 2 penetrate a side wall part 10 of the case 1 and are connected to the header parts 7 a and 7 b provided on an outer surface side of the side wall part 10. As a result, water supplied from the outside to the header part 7 a passes through each heat transfer pipe 2, reaches the header part 7 b, and outflows. In such a process, the water is heated by combustion gas.

The plurality of heat transfer pipes 2 are divided into first and second heat transfer pipes 2A and 2B, and these are provided with first and second recessed parts 3A and 3B. This point will be described in more detail below.

The plurality of heat transfer pipes 2 are arranged in a lateral width direction of the case 1 (a left to right direction in FIG. 2, which is an example of the y direction in the disclosure), and the heat transfer pipes 2 adjacent to each other are provided to be misaligned with each other by an appropriate dimension La in the vertical height direction. In the present embodiment, one having a lower height is the first heat transfer pipe 2A (2), and the other having a higher height is the second heat transfer pipe 2B (2). These first and second heat transfer pipes 2A and 2B are misaligned such that the plurality of straight pipe parts 20 do not overlap each other in the vertical height direction. However, parts of the plurality of curved pipe parts 21 overlap each other (places indicated by reference numeral OV in FIG. 3 are overlapping parts OV).

As shown in FIG. 4, the first recessed part 3A is provided at a place corresponding to the above-mentioned overlapping part OV in each curved pipe part 21 of the first heat transfer pipe 2A and is recessed in the y direction. As is clearly shown in FIGS. 5A to 5E, the first recessed part 3A is disposed to be offset from a center line CL of each curved pipe part 21 and is provided on each of a pair of left and right side surface parts (a pair of side surface parts facing the y direction) of each curved pipe part 21. That is, each curved pipe part 21 is provided with a pair of left and right first recessed parts 3A and these face each other. As a result, a width Lb of a formation part of the pair of first recessed parts 3A of each curved pipe part 21 is smaller than a width Lc of other parts (corresponding to an outer diameter of the heat transfer pipe 2). The first recessed part 3A can be formed by partially pressing each curved pipe part 21.

The second recessed part 3B is provided at a place corresponding to the above-mentioned overlapping part OV in each curved pipe part 21 of the second heat transfer pipe 2B and is recessed in the y direction. Here, the second heat transfer pipe 2B in the present embodiment has a configuration in which the first heat transfer pipe 2A is turned upside down. Therefore, similarly to the above-mentioned first recessed part 3A, the second recessed part 3B is provided on each of the pair of left and right side surface parts of each curved pipe part 21, and the pair of left and right second recessed parts 3B face each other.

The plurality of first and second heat transfer pipes 2A and 2B are set to be in a state in which the formation parts of the first recessed parts 3A and the formation parts of the second recessed parts 3B are fitted to each other, that is, a state in which the formation parts of the second recessed parts 3B are fitted in the first recessed parts 3A, and the formation parts of the first recessed parts 3A are fitted in the second recessed parts 3B (see FIG. 2 and FIGS. 6A to 6C).

Next, an operation of the above-mentioned heat exchanger HE will be described.

First, as described above, in the overlapping parts OV of each curved pipe parts 21 of the first and second heat transfer pipes 2A and 2B, the formations parts of the first and second recessed parts 3A and 3B are fitted to each other. For this reason, as shown in the partial enlarged view of FIG. 2, the straight pipe parts 20 of the first and second heat transfer pipes 2A and 2B can be disposed to overlap each other by an appropriate dimension Ld in the lateral width direction of the case 1. As a result, it is possible to reduce the overall width L1 of the plurality of heat transfer pipes 2 and reduce the overall size of the heat exchanger HE.

The first and second heat transfer pipes 2A and 2B do not have a configuration in which the entire curved pipe part 21 is formed in a flat shape, but have a configuration in which the first and second recessed parts 3A and 3B are only partially provided in each curved pipe part 21. For this reason, it is possible to reduce the resistance (flow path resistance) when water flows through each curved pipe part 21. Further, the first and second recessed parts 3A and 3B are relatively small in size, and thus when these are formed on each curved pipe part 21 by pressing, the amount of pressing (an amount of deformation) can be reduced. Therefore, the residual stress caused by the pressing can be reduced, and the first and second heat transfer pipes 2A and 2B can be made excellent in durability strength. Further, when the amount of pressing on the curved pipe part 21 is large, the heat transfer pipe 2 may be deformed so that both end parts of the curved pipe part 21 are widened, but according to the present embodiment, it is possible to eliminate such a risk.

Further, in the present embodiment, any of the first and second recessed parts 3A and 3B is provided on each of the pair of left and right side surface parts of each curved pipe part 21. For this reason, as compared with the case in which any of the first and second recessed parts 3A and 3B is provided in only one of the pair of side surface parts, for example, as in another embodiment, which will be described later, it is possible to reduce the overall width L1 of the plurality of heat transfer pipes 2 while reducing depth dimensions of the first and second recessed parts 3A and 3B. If the depth dimensions of the first and second recessed parts 3A and 3B are increased, the residual stress when these parts are pressed may increase, but according to the present embodiment, it is possible to appropriately avoid such a risk.

As described above, the second heat transfer pipe 2B has a configuration in which the first heat transfer pipe 2A is turned upside down. For this reason, manufacturing costs of the heat exchanger HE can be reduced as compared with the case in which the first and second heat transfer pipes 2A and 2B having different shapes and sizes are used.

FIGS. 7 to 12C show other embodiments of the disclosure. In these figures, elements that are the same as or similar to those of the above embodiment are designated by the same reference numerals as those of the above embodiment.

In the embodiment shown in FIGS. 7 to 8C, any of the first and second recessed parts 3A and 3B is provided only on one side surface part of the pair of left and right side surface parts of the curved pipe parts 21 of the first and second heat transfer pipes 2A and 2B. Either of the first recessed part 3A or the second recessed part 3B is not provided on the other side surface part. The second heat transfer pipe 2B corresponds to a configuration in which the first heat transfer pipe 2A is turned upside down, as in the above embodiment.

As is clearly shown in FIG. 8C, the formation part of the second recessed part 3B is fitted to the formation part of the first recessed part 3A on one side of the curved pipe part 21 of the first heat transfer pipe 2A. On the other hand, places at which the first and second recessed parts 3A and 3B are not formed are disposed to face and come into contact with or face and come closer to each other on the other side opposite to the one side of the curved pipe part 21 of the first heat transfer pipe 2A.

In the present embodiment, as shown in FIG. 8B, the straight pipe parts 20 of the first and second heat transfer pipes 2A and 2B can overlap each other by an appropriate dimension Le in the lateral width direction of the case 1. Therefore, similarly to the above-described embodiment, the overall width of the plurality of heat transfer pipes 2 (2A and 2B) can be reduced. As compared with the embodiment in which the first and second recessed parts 3A and 3B are provided in each of the pair of left and right side surface parts of the curved pipe part 21, it is also possible to simplify the configuration of each heat transfer pipe 2.

In the embodiment shown in FIGS. 9 to 10C, the first heat transfer pipe 2A is provided with a pair of first recessed parts 3A on the pair of left and right side surface part of each curved pipe part 21, whereas the second heat transfer pipe 2B is not provided with a part corresponding to the second recessed part 3B. For the second heat transfer pipe 2B, an existing meandering pipe can be used. As is clearly shown in FIG. 10C, parts of the curved pipe parts 21 of the second heat transfer pipes 2B are fitted into the pair of first recessed parts 3A of the first heat transfer pipe 2A as it is.

In the present embodiment, as shown in FIG. 10B, the straight pipe parts 20 of the first and second heat transfer pipes 2A and 2B can overlap each other by an appropriate dimension Lf in the lateral width direction of the case 1. Therefore, similarly to the above-described embodiment, it is possible to reduce the overall width of the plurality of heat transfer pipes 2 (2A and 2B). Since an existing heat transfer pipe having no second recessed part 3B can be used for the second heat transfer pipe 2B, it is possible to reduce the manufacturing costs.

In the embodiment shown in FIGS. 11 to 12C, the first heat transfer pipe 2A is provided with the first recessed part 3A only on one of the pair of left and right side surface parts of each curved pipe part 21. The second heat transfer pipe 2B is not provided with a part corresponding to the second recessed part 3B. As is clearly shown in FIG. 12C, in the first heat transfer pipe 2A, a part of the curved pipe part 21 of the second heat transfer pipe 2B is fitted in the first recessed part 3A, whereas an outer circumferential surface of the curved pipe part 21 of the second heat transfer pipe 2B abuts or comes closer to one side opposite to the first recessed part 3A.

In the present embodiment, as shown in FIG. 12B, the straight pipe parts 20 of the first and second heat transfer pipes 2A and 2B can overlap each other by an appropriate dimension Lg in the lateral width direction of the case 1. Therefore, similarly to the above-described embodiment, it is possible to reduce the overall width of the plurality of heat transfer pipes 2 (2A and 2B). For the second heat transfer pipe 2B, an existing heat transfer pipe having no second recessed part 3B can be used, and the first heat transfer pipe 2A is provided with the first recessed part 3A only on one side, and thus the manufacturing costs can be reduced.

The disclosure is not limited to the contents of the above-described embodiment. The specific configuration of each part of the heat exchanger and the water heating device according to the disclosure can be redesigned in a various way within the scope intended by the disclosure.

The specific shape, size, depth, or the like of the first and second recessed parts are not limited. It does not matter if their shapes or the like are different between in the case in which the first and second recessed parts are provided on each of the pair of left and right side surface parts of the curved pipe parts of the heat transfer pipe, and in the case in which they are provided on only one of them.

In the above embodiment, among the plurality of heat transfer pipes misaligned in the vertical height direction, one on the lower height side is set as the first heat transfer pipe, and the other is set as the second heat transfer pipe, but the disclosure is not limited thereto and may be the reverse of the embodiment described above.

Further, in the above-described embodiment, the x and y directions indicated in the disclosure are horizontal directions, and the z direction corresponds to the vertical height direction, but the disclosure is not limited thereto, and these directions can be appropriately selected. For example, it is also possible to have a configuration in which a plurality of heat transfer pipes lying substantially horizontally are stacked (arranged) in the vertical height direction, that is, a configuration in which the y direction is the vertical height direction. In this case, the width of the entire plurality of heat transfer pipes in the vertical height direction can be reduced, and reduction in size of the heat exchanger can be achieved.

The heat transfer pipe has a meandering shape, but the specific size, number, material, or the like of the straight pipe part and the curved pipe part are not limited. The heat transfer pipe can be formed by bending a single pipe member, but instead of this, the straight pipe part and the curved pipe part may be formed of separate members, and these may be integrally connected.

The heating medium indicated in the disclosure is not limited to combustion gas generated by the burner and may be high-temperature exhaust gas or the like. The heat exchanger according to the disclosure can be used for anything other than latent heat recovery. The water heating device indicated in the disclosure is a concept including not only a hot water supply device for general hot water supply and bath hot water supply, but also a water heating device for hot water heating or snow melting. 

What is claimed is:
 1. A heat exchanger comprising: a plurality of heat transfer pipes that have a form of a meandering shape, in which a plurality of straight pipe parts that extend in an x direction among x, y, and z directions intersecting with each other and are arranged at intervals in the z direction are connected in a series via a plurality of curved pipe parts, and are located in a region through which a heating medium flows and stacked in the y direction, wherein the plurality of heat transfer pipes comprises a first heat transfer pipe and a second heat transfer pipe, which are adjacent to each other in the y direction and misaligned with respect to each other in the z direction such that, in a view in the y direction, the plurality of straight pipe parts are in a non-overlapping state and parts of the plurality of curved pipe parts are in an overlapping state, and wherein a first recessed part recessed in the y direction is provided in a part of each curved pipe part of the first heat transfer pipe, and wherein a part of each curved pipe part of the second heat transfer pipe is fitted into the first recessed part.
 2. The heat exchanger according to claim 1, wherein each curved pipe part of the first heat transfer pipe comprises a pair of side surface parts facing in the y direction, and the first recessed part is provided in each of the pair of side surface parts.
 3. The heat exchanger according to claim 1, wherein each curved pipe part of the first heat transfer pipe comprises a pair of side surface parts facing in the y direction, and the first recessed part is provided only on one of the pair of side surface parts.
 4. The heat exchanger according to claim 1, wherein a second recessed part recessed in the y direction is provided in a part of each curved pipe part of the second heat transfer pipe, and respective formation places of the first and second recessed parts are fitted to each other.
 5. The heat exchanger according to claim 1, wherein the second heat transfer pipe coincides with a configuration of a heat transfer pipe having a same shape and size with the first heat transfer pipe and has been turned upside down.
 6. The heat exchanger according to claim 1, wherein, the first and second heat transfer pipes are configured by using metal round pipes.
 7. The heat exchanger according to claim 1, further comprising: a case which houses the first and second heat transfer pipes therein and the heating medium is supplied to an inside of the case; and a pair of header parts for inflow of water and outflow of hot water for each of the first and second heat transfer pipes.
 8. The heat exchanger according to claim 1, wherein the x and y directions are both horizontal directions, and the z direction is a vertical height direction.
 9. A water heating device comprising the heat exchanger according to claim
 1. 